1994 4-Runner oil pressure issues

[Really Old Guy]

Hello,
I've been a member for a long time, but just hung out in the shadows and rarely posted anything. I've followed this thread long enough to know that someone out there will be able to help me. Thanks in advance.
My grandson recently purchased a 1994 4-Runner with about 175k on the odometer. He told me that when he drives it long enough to get it warmed up the oil pressure drops to around 20psi. It has a 3.0 liter v-6. Is this a common problem and is there anything we can do to help it short of a rebuild?

 

[Pike2350]

I'm no mechanic but I know the 3.0 is notorious for head gasket issues. This can lead to low oil pressure but obviously the coolant in oil will be a bigger issue. Maybe drain the oil and check it's condition.

 

[bryson]

I'd check the gauge, connection, sender, etc. OEM gauges are notoriously crappy no matter the vehicle.

In other words, verify that the oil pressure is actually low before trying to figure out why.

 

[bryson]

Also, is that 20psi oil pressure at idle? If so, I wouldn't worry about it. That sounds like a normal idle oil pressure to me. Anything over idle I'd hope to see ~10psi per 1000 RPM.

What weight oil is in the engine?

 

[gorillaxj]

I would agree with the above. 10psi for every 1k RPM is a good standard. How have you verified 20psi? stock gauges are typically
H - L unless I am miss remembering.

Typically the diaphragm in the sender goes bad unless the gauge stops working all together at times. I would start by knowing oil pressure when hot at idle (after engine sits idle if for 20-30 seconds) and at 2500 RPM after 30 seconds.

 

[Really Old Guy]

Thanks for the good information. I'll check out everything mentioned.